Increasing evidence suggests that acetaldehyde, the first and genotoxic metabolite of ethanol, mediates the carcinogenicity of alcoholic beverages. Ethanol is also contained in a number of readyto-use mouthwashes typically between 5 and 27% vol. An increased risk of oral cancer has been discussed for users of such mouthwashes; however, epidemiological evidence had remained inconclusive. This study is the first to investigate acetaldehyde levels in saliva after use of alcohol-containing mouthwashes. Readyto-use mouthwashes and mouthrinses (n 5 13) were rinsed in the mouth by healthy, nonsmoking volunteers (n 5 4) as intended by the manufacturers (20 ml for 30 sec). Saliva was collected at 0.5, 2, 5 and 10 min after mouthwash use and analyzed using headspace gas chromatography. The acetaldehyde content in the saliva was 41 6 15 lM, range 9-85 lM (0.5 min), 52 6 14 lM, range 11-105 lM (2 min), 32 6 7 lM, range 9-67 lM (5 min) and 15 6 7 lM, range 0-37 lM (10 min). The contents were significantly above endogenous levels and corresponding to concentrations normally found after alcoholic beverage consumption. A twice-daily use of alcohol-containing mouthwashes leads to a systemic acetaldehyde exposure of 0.26 lg/kg bodyweight/day on average, which corresponds to a lifetime cancer risk of 3E26. The margin of exposure was calculated to be 217,604, which would be seen as a low public health concern. However, the local acetaldehyde contents in the saliva are reaching concentrations associated with DNA adduct formation and sister chromatid exchange in vitro, so that concerns for local carcinogenic effects in the oral cavity remain. ' 2009 UICC

For the first time, the pattern of co-exposure to fragrance ingredients in important categories of cosmetic products has been described. The observations illustrate and quantify the 'cocktail' of fragrance allergens that may facilitate sensitization.

High frequencies of sensitization may be put into perspective by the frequent use of certain preservatives. Despite infrequent use, others (with higher potencies or too high use concentrations) may turn out to be associated with an increased risk. Hazard assessment should be supplemented by risk assessment.

The pattern of co-exposure to preservatives in important categories of cosmetic products illustrates the 'cocktail' of allergens that may facilitate sensitization, although, conversely, the combination of preservatives allows individual use levels to be kept lower, thereby possibly reducing sensitization risk.

The frequent co-occurrence of UV filters in cosmetic products possibly facilitates sensitization, and may explain why patients often react to chemically unrelated UV filters.